This is referred to as: spontaneous recovery
Spontaneous recovery is a theory of learning and memory which involves unexpected and recurrence of a conditioned response after a period of reduced response or delay. Spontaneous recovery is associated with classical conditioning and operant conditioning. Extinction will happen quickly after a spontaneous recovery, if the conditioned and unconditioned stimulus is not connected.
i believe the answer to be B
High melting point
Good conductors of heat and electricity
Lustrous (shiny)
Malleable (can be hammered)
For him they were just discrete physical units of inheritance. Johanson coined the term "gene" and people started calling them genes. Today for us these factors are parts of DNA, the base sequences that carry the biological information to determine a trait. Mendel factors are alleles of genes.
The probability of having a second child presenting the desease is 25% (i think so)