He came to Galveston, Texas, in 1820 and lived at Nacogdoches for the rest of his life.
 
        
             
        
        
        
Answer:
 D. is a hobby
Explanation:
According to my research on the English language, I can say that based on the information provided within the question the correct statement for this question would be "is a hobby". Therefore the whole correct sentence would be "Stamp collecting is a hobby sometimes used in the schools to teach economics and social studies."
I hope this answered your question. If you have any more questions feel free to ask away at Brainly.
 
        
             
        
        
        
Answer: a. testing effect
Explanation:
Testing effect is a type of threat to internal validity of an experiment. Internal validity is assessing whether a factor makes a difference in an experiment or not and if it does, whether there is adequate evidence to support this correlation.
Testing as a threat to internal validity is when a second test is taken on the outcome of a first test. Other internal validity threats are history, maturation, instrument modifications.
 
        
             
        
        
        
Answer:
Parasomnia
Explanation:
Parasomnia is a sleep disorder that can include sleep walking, sleep talking, nightmares, night terrors, and chest pain. It is usually seen in childhood and can worsen into adolescence and adulthood.