B. tu piensas
c and d are talking to more than one person
a is talking about one person but it is refering he or she, el o ella
b is for you, tu
Tú casa es grande.

The difference between "tú" and "usted" depends on the formality. "Tú" is used <u>when talking to friends or relatives (informal)</u> while "usted" is used <u>when talking to older people or a person of high social rank (formal)</u>.
In this case we want to write the <u>informal</u> form of "tú", so we use "tú". Also, when dealing with <u>permanent states</u>, the verb "ser" (to be) is used.
Dhaka Topi
Daura Suruwal
Dhoti
Lungi
Gunyou Cholo
Sari
Kurta Suruwal
Ésa would be the correct answer
1. Bicicleta
3. No apagar las luces de tu casa, cuando no la usas.
4. No tala de árboles. No quemar cosas.
5. Recoger basura o no tirar basura en los parques.
6. Tirar basura en los ríos.
I’m not sure what exactly you needed to do. I guessed you needed to put an example to each statement.
I hope this helped you.
If it didn’t, you let me know, please.