Arduino random LED on

Using Arduino LEDs and Multiplexing
#1

I have a project which has two options No. 1 Randomly turn on one LED from a group of 6 LED (Relay Board) No.2 randomly turn on one LED from a group of 2 LED (Relay Board) The selection of the desired option happens with a switch.

I found this code online which is just perfect for 6 LED but I don’t know how to add the selection of the options in it, how to do it?

int timeShowRandom = 3000;
int timeShowDecision = 6000;
int timeBlink = 100;
int buttonPin = 2;
int buttonPress = false;
int randomNumber;
int previousNo = 0;
int timePassed = 0;

void setup() {  
  // Set button pin
  pinMode(buttonPin, INPUT);
  // Set output pins  
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(7, OUTPUT);
}

void getRandomNo() {
 int rand = random(7,13);
  if (rand == previousNo) {
   getRandomNo();
  } else {
    randomNumber = rand;
    previousNo = randomNumber;
  }
}

void loop() {
 if (digitalRead(buttonPin) == HIGH && buttonPress == false ) {
     buttonPress = true;
  } if (buttonPress == true && timePassed <= timeShowRandom) {
    getRandomNo(); // Get random pin number
    digitalWrite(randomNumber, LOW);
    delay(timeBlink);
    digitalWrite(randomNumber, HIGH);
    delay(timeBlink);
   timePassed = timePassed + (timeBlink * 2);
  } else if(buttonPress == true) {
    digitalWrite(random(7,13), LOW); // Set random pin on
    delay(timeShowDecision); // For x seconds
    buttonPress = false; // Set button to be enabled again
    timePassed = 0;
  }
  else {
    // Reset all output pins
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(12, HIGH);
    digitalWrite(9, HIGH);
    digitalWrite(8, HIGH);
    digitalWrite(7, HIGH);
  }   
}
#2

Here's one way

byte selectionPin = 2; // or 3,4,5, whatever
void setup(){
pinMode (selectionPin, INPUT_PULLUP); // Gnd or, or let if be pulled high internally
}

void loop(){
if (digitalRead(selectionPin) == LOW){
// run option 1
}
else {
// run option 2
]
#3