<h2><u>
Answer:</u></h2>
If two people do not get along each other, they will tend to fight (<u>pelearse </u>in Spanish).
<u>Pelearse</u> is a pronominal verb, this means the verb <em><u>pelear</u></em> (to fight) is used with the addition of the reflexive pronoun <u><em>se</em></u>, in order to <u>emphasize</u> the fact that two or more people fight.
In this case are a brother and a sister <em>ellos</em> (they).
In general, a <u>pronominal verb</u> is the one that needs to be conjugated with a <u>reflexive pronoun</u>, which agrees in person and number with the subject, <u>to express reflexivity and in some cases emphasis</u>.
Here the <u>Reflexive Pronouns</u> according to the subject are:
1st person singular: Yo (I) <em><u>me </u></em>
2nd person singular: Tú (You) <em><u>te</u></em>
3rd person singular: Él/Ella/eso/esa (He, She, It) <em><u>se</u></em><em><u>
</u></em>
1st person plural: Nosotros (we) <em><u>nos </u></em>
2nd person plural: Ustedes (You) (In latinAmerica) <em><u>se </u></em>/ Vosotros (In Spain) <em><u>os</u></em><em><u> </u></em>
3rd person plural: Ellos/Ellas (They) <em><u>se</u></em>
It should be noted that these reflexive pronouns <u>are used to change the meaning of the verb, accentuate the action or indicate that the action directly affects the subject</u>. And generally <u>it has no object</u> (it is an intransitive verb).
In this case, to the verb <em><u>pelear</u></em>, the reflexive pronoun <em><u>se</u></em> is added and it becomes <em><u>pelearse</u></em> (plural). This action emphasizes the fact that two people (ellos/they) fight each other.
Therefore, the right answer is B:
<h2>Pelearse
</h2>
The other words are not correct, because they are not related to this context.
Coleccionar means <em>to collect
</em>
Saltar la Cuerda means <em>to Jump the rope
</em>
Ofrecer means <em>to offer
</em>
<em>
</em>
So, it is clear that if two people did not get along, they would not do this kind of activities together.