Erica tiene bloques en la bolsa.
Erica los tiene en la bolsa.
b.) The direct object pronoun "los" is correct because "bloques" is a masculine plural noun. In Spanish, the direct object pronouns are "lo" for masculine singular, "la" for feminine singular, "los" for masculine plural, and "las" for feminine plural. Since "bloques" refers to multiple items ("bloques" is masculine and plural), we use "los" to substitute for "bloques."