Answer:
This is a conversation between Eric and Roberto, in which Eric expresses joy because they are going to take a bath in the lake.
If you are going to swim in a lake, generally you need a bathing suit or swimming suit, which in spanish is translated to traje de baño.
You won’t need a Jacket (Chaqueta), a sleeping bag (saco de dormir), nor a pair of sandals or flips flops (sandalias), to swim in the lake.
Therefore, the right answer is:
traje de baño
Below is the conversation in English:
Eric: It's good that we came to the lake! Now we can take a bath.
Roberto: Oh, no! I forgot to bring my swimming suit
