The correct answer is D) In solutions you cannot see the separate substances.
Step-by-step explanation:
In a solution, one substance dissolves in another, for example, salt dissolves in water. This process results in a homogeneous substance or mixture, in which the particles of the original substances cannot be seen separately. Also, these substances are chemically combined forming a new substance.
On the other hand, in a mixture such as combining sand and water, the particles of each substance are physically, but not chemically combined. Due to this, particles of each substance can be identified in the mixture, and these can be separated. According to this, the statement that summarizes the observation presented is "in solutions you cannot see the separate substances" considering in solutions the result is a homogeneous substance.