Abrother and sister who did not get along as kids most likely did which of the following when they were young? a. coleccionar b. pelearse c. saltar a la cuerda d. ofrecer

If two people do not get along each other, they will tend to fight (pelearse in Spanish).

Pelearse is a pronominal verb, this means the verb pelear (to fight) is used with the addition of the reflexive pronoun se, in order to emphasize the fact that two or more people fight.

In this case are a brother and a sister ellos (they).

In general, a pronominal verb is the one that needs to be conjugated with a reflexive pronoun, which agrees in person and number with the subject, to express reflexivity and in some cases emphasis.  

Here the Reflexive Pronouns according to the subject are:

1st person singular: Yo (I) me

2nd person singular: Tú (You) te  

3rd person singular: Él/Ella/eso/esa (He, She, It) se

1st person plural: Nosotros (we) nos

2nd person plural: Ustedes (You) (In latinAmerica) se / Vosotros (In Spain) os    

3rd person plural: Ellos/Ellas (They) se  

It should be noted that these reflexive pronouns are used to change the meaning of the verb, accentuate the action or indicate that the action directly affects the subject. And generally it has no object (it is an intransitive verb).

In this case, to the verb pelear, the reflexive pronoun se is added and it becomes pelearse (plural). This action emphasizes the fact that two people (ellos/they) fight each other.

Therefore, the right answer is B:

The other words are not correct, because they are not related to this context.

Coleccionar means to collect

Saltar la Cuerda means to Jump the rope

Ofrecer means to offer

So, it is clear that if two people did not get along, they would not do this kind of activities together.